A laminated multilayer film substrate for use in the production of banknotes having an oriented polypropylene core layer and at least one high density polyethylene layer on each side of the oriented polypropylene layer. The core layer contains microcavities formed by the addition of a cavitating agent. The resultant films exhibit good embossability, dead-fold characteristics and other properties, making them highly suited for the production of bank notes and other security documents.

The present invention relates to a multilayer film for use in the production of paper-like products such as bank notes, security documents, including travelers and bank checks, and to a method for their production. More particularly, the present invention relates to a multilayer film having the characteristics of the high quality papers typically employed in the production of bank notes and security documents.
In the production of bank notes, security documents and the like, rag paper has been employed for over 300 years. As is well known, rag paper has several properties which are highly desirable in such applications, including dead foldability, tear resistance, printablilty and embossability.
These highly desired properties may be characterized as follows: deadfold is the ability of a substrate to be creased or folded and to retain the fold without opening. Tear resistance is the ability of a substrate to resist both initiated and uninitiated tears and punctures. Printability is the ability of the substrate to adsorb and bond inks used during the lithographic printing process. Embossability is the ability of the substrate to deform under the pressures of the intaglio printing process to form a raised image on the resulting bank note or security document, with the intaglio ink remaining on the raised, deformed region resulting in a high degree of tactility or feel to the bank note or security document. As may be appreciated, these properties combine to give bank notes and the like their familiar feel and functionality.
With the advent of color copiers and computer graphic scanners, the counterfeiting of bank notes has markedly increased. While there are active programs underway by major currency paper producers to make their substrate more secure through the use of watermarks, metallized threads and optical variable devices (OVD""s), such as photochromics, holographics, and diffraction gratings, at this time, these efforts do not appear to hold much promise of thwarting counterfeiters.
Security features can be incorporated into or onto the bank note, including reverse printing of the note to protect the security devices and the print.
Australian Patent No. 488,652, discloses an approach to the production of security articles, particularly bank notes, and describes the serious problems which confront conventional bank notes with respect to forgery. The bank note disclosed therein comprises a substrate of opaque thermoplastic sheet material intimately bonded to a web of woven or unwoven thermoplastic fibers, the substrate being printed as desired and having bonded thereon one or more optically-variable security devices. The fibrous web was employed to impart durability, crumple-resistance and tear-strength to the note. Where a security device, such as a Moire pattern, was employed which depended for its optically variable properties upon the transmission of light, it was necessary to punch out a hole in the substrate, insert the device and bond it in place with further layers of transparent plastic sheet material.
Although samples of bank notes formed according to the disclosure of Australian Patent No. 488,652 were said to have performed most satisfactorily with respect to the durability and security of conventional notes, they were found to be rather complex in construction and relatively expensive to produce. Moreover, when transmission security devices were laminated between layers in the substrate, an area of weakness and high stress was created which reduced both durability and security.
Other disclosures relating to anti-counterfeiting techniques include U.S. Pat. Nos. 4,095,217 and 4,281,208, which relate to the use of a liquid crystal device driven by a photovoltaic element, such as a solar cell or an amorphous silicon material.
U.S. Pat. No. 4,472,627 relates to currency or other valuable documents containing a liquid crystal/photovoltaic device which produces a coded display in response to artificial or ambient light. The device can function both as an anti-counterfeiting deterrent and also as a means for permitting a user to easily authenticate the validity of a document containing such a device.
U.S. Pat. No. 4,536,016 discloses a security token, such as a bank note or identity card, which comprised a sheet-like substrate made up from film of transparent biaxially oriented polymer coated with layers of opaque and heat activated adhesive material. The opaque layer is applied in such a way as to leave a transparent area for inspection of a security device, for example, a diffraction grating, incorporated in the polymer film. The substrate could bear printed or other identifying indicia and was protected with an intimately bonded layer of transparent polymeric material.
The substrate employed in U.S. Pat. No. 4,536,016 was based on the use of oriented polypropylene (OPP). After several commemorative bank note printings, while meeting many of the requirements for a bank note substrate, the plastic bank notes were found to fail in three major areas. First, the OPP substrate did not dead fold, causing problems in that the film retains either a flat or curved form, jamming cash registers and automatic handling equipment. Second, the OPP substrate has poor initiated tear resistance in the processing of currency, which quite frequently creates nicks on the edges of bills, resulting in catastrophic tears. Finally, the OPP product did not exhibit the tactility of paper currency, due to the fact that OPP does not emboss well during the intaglio process.
Oriented high density polyethylene films have been employed in the area of plastic packaging. Such films, biaxially oriented to a degree of greater than 6.5 times in both the machine direction (MD) and the transverse direction (TD) are described in British Patent 1,287,527. U.S. Pat. No. 4,680,207 relates to imbalanced biaxially oriented films of linear low density polyethylene oriented up to six times in the machine direction, and up to three times in the transverse direction but less than in the machine direction.
U.S. Pat. No. 5,618,630 relates to a three-ply mulitlayer film structure for the production of banknotse.
While the aforementioned films have been shown to offer certain advantages over the prior art and generally meet the requirements for which they were designed, a need still exists for a film which provides the characteristics of a high quality, rag-type paper of the type typically employed in the production of bank notes and security products.
Therefore, it is an object of the present invention to provide a multilayer film having the characteristics of a high quality rag paper.
It is another object of the present invention to provide such a multilayer film which possesses the dead-fold characteristics of high quality papers while being easy to manufacture and reasonably durable.
It is a further object of the present invention to provide a multilayer film which possesses a high degree of tear resistance to both initiated and uninitiated tears and punctures in at least one direction.
It is yet another object of the present invention to provide a multilayer film which possesses the printability and embossability of a high quality paper.
It is still a further object of the present invention to provide a multilayer film which possesses a high degree of resistance to curling at higher temperatures, e.g., above 150xc2x0 F.
Still another object of the invention is to provide a multilayer film which is suitable for banknote production from which it is difficult to abrade inks resulting in banknotes of long service life. Such films can achieve high levels of durability without overlaying the inked surface with protective coatings such as lacquers or polyurethanes.
Other objects and the several advantages of the present invention will become apparent to those skilled in the art upon a reading of the specification and the claims appended thereto.
The multilayer film of the present invention is an opaque three-ply structure. In a preferred embodiment, at least one layer of oriented polypropylene (OPP) is surrounded by at least one layer of high density polyethylene (HDPE) on either side of the OPP layer.
The multilayer film of the present invention exhibits good performance in repetitive fold tests. The multilayer film structure of the present invention also has high tensile strength in both the oriented and unoriented direction.
In accordance with the present invention, there is provided a curl-resistant, cross-sectionally symmetrical, laminated multilayer film substrate for use in the production of banknotes, security papers and the like comprising:
(a) an imbalanced biaxially oriented first layer having inner and outer sides, comprising at least about 50 weight percent of a high density polyethylene having a density of at least about 0.94, said first layer being oriented in at least a first direction to a degree which is at least three times less than the degree of orientation present in a second direction substantially normal to the first direction;
(b) a balanced biaxially oriented second layer having inner and outer sides, comprising a cavitating agent and at least about 90 wt. % polypropylene, said second layer being oriented in at least a first direction, at an orientation ratio of at least 4:1, and oriented in a second direction substantially normal to said first direction, at an orientation ratio of at least 6:1;
(c) an imbalanced biaxially oriented third layer having inner and outer sides, comprising at least about 50 weight percent of a high density polyethylene having a density of at least about 0.94, said third layer being oriented in at least a first direction to a degree which is at least three times less than the degree of orientation present in a second direction substantially normal to the first direction; and
(d) a laminating adhesive resin disposed between the inner sides of (a) and (c), said second layer being laminated to said first and third layers so that the first direction of orientation of said third layer is substantially aligned with the first direction of orientation of said first layer and wherein (a) further comprises a coextruded propylene copolymer skin on its inner side.
In forming the multilayer film of the present invention at least one layer of the substrate comprises oriented polypropylene and a cavitating agent. The use of oriented polypropylene in the core results in high tensile properties and high performance in repetitive fold tests. The use of a cavitating agent in the core offers good opacity which minimizes the need for a heavy opacifying coating.
It is preferred to use oriented polypropylene (OPP) in the core. However, other biaxially oriented polymers of a comparable tensile strength, such as linear low density polyethylene (LLDPE), nylons or polyester may also be used. It is preferred that the OPP core be free of any additives, for example, anti-static agents and silicone, which have an impact on adhesion to other layers.
The core layer of the present invention comprises a plurality of voids formed by cavitation about a solid cavitation agent, such as polybutylene terephthalate and/or calcium carbonate. Polybutylene terephthalate, e.g., 0.2 to 2 microns in diameter, as described in U.S. Pat. Nos. 5,288,548; 5,264,277; and 4,632,869, the contents of which are incorporated herein by reference, is a suitable cavitation agent. The spherical particles form microvoids on orientation, resulting in a white opaque product.
The use of a cavitating agent in the core layer offers good opacity, which reduces the need for a heavy opacifying coating and thus reduces the weight of the banknote. The reduced weight improves set off when freshly printed banknotes are stacked in sheets at the end of the press. The notes at the bottom of the stack will be exposed to less pressure from the reduced stack weight.
In forming the multilayer film substrates for use in the production of the bank notes and other security documents of the present invention, at least two layers of the substrate are to contain a major proportion of a high density polyethylene (HDPE) having a density of at least about 0.94, preferably at least about 0.945. These film layers may be composed exclusively of a single HDPE resin, a mixture of HDPE resins, or of HDPE containing a minor proportion of another polymeric material, such as low density polyethylene (LDPE), linear low density polyethylene (LLDPE), polypropylene, ethylene vinyl alcohol (EVOH) copolymer, ethylene propylene (EP) copolymer, ethylene propylene butene-1 (EPB) copolymer, polyetser or nylon, although a single HDPE resin or a blend of HDPE resins is particularly preferred in the practice of the present invention. Films made with either a blend of HDPE resins or with microcrystalline wax have been found to reduce the splittiness of the film which manifests itself as the tendency of the film to break in the TD direction.
When blends of HDPE polymers are employed, such blends can comprise two or more polymers all of which preferably have densities of 0.94 or greater. Blends of HDPE polymers advantageously comprise a major proportion of HDPE having a melt index of 0.6 to 1.2 and one or more polymers having a different melt index.
Terblends may also be desirable. Suitable terblends generally comprise 50 to 98 weight percent, preferably 84 to 96 weight percent of HDPE having a density of 0.96 or higher and a melt index of greater than 0.5 to about 2.0; 1 to 25 weight percent, preferably 3 to 8 weight percent of HDPE having a density of 0.94 or greater and a melt index of 0.1 to 0.5; and 1 to 25 weight percent, preferably 3 to 8 weight percent, of HDPE having a density of 0.96 or higher and a melt index of greater than 2 to about 8. Preferably, the second and third HDPE polymers which are minor components are present in about equal amounts.
As is particularly preferred, the film substrate of the present invention includes a) a first layer comprising at least about 50 weight percent of a high density polyethylene having a density of at least about 0.94, the first layer oriented in at least a first direction, e.g., machine direction (MD), to a degree which is at least three times less than the degree of orientation present in a second direction substantially normal to the first direction, e.g., transverse direction (TD); (b) a second layer comprising at least about 90 weight percent polypropylene, the second layer being oriented in at least a first direction e.g., machine direction (MD), at an orientaion ratio of at least 3:1, and oriented in a second direction substantially normal to said first direction e.g., transverse direction (TD), at an orientation ratio of at least 6:1; and c) a third layer also comprising at least about 50 weight percent of a high density polyethylene having a density of at least about 0.95, the third layer also oriented in at least a first direction, e.g., MD, to a degree which is at least three times less than the degree of orientation present in a second direction, e.g., TD, substantially normal to the first direction, the third layer being laminated to the film substrate so that the first direction of orientation of the third layer is substantially parallel to (or aligned with) the first direction of orientation of the first layer.
A method of producing HDPE films with imbalanced biaxial orientation is disclosed in U.S. Pat. No. 4,870,122, the contents of which are incorporated by reference in their entirety.
As may be appreciated, to achieve the object of improved tear resistance in a multilayer film of the type describe herein, it has been discovered that imbalanced biaxially oriented HDPE films, laminated so that their primary directions of orientation are aligned substantially parallel to each other, can exhibit increased tear resistance where an orientable laminating resin, e.g., polyurethane, is disposed between the layers and subjected to orienting so that the primary direction of orientation in the oriented resin is substantially normal to the primary direction of orientation of the first and third HDPE film layers. In one embodiment, such orientation in the primary direction of orientation of the laminating adhesive resin is achieved during the laminating step itself, preferably in the machine direction (MD).
The degree of orientation of the HDPE film layers is an important aspect of this invention inasmuch as the proper degree of orientation provides desirable physical properties. Although higher density HDPE resin having a density of 0.957 or greater can be made directly into thin films by cast extrusion, problems of curling, uniformity and flatness exist. Accordingly, thin HDPE films of about 0.8 to 1.5 mils having the best balance of properties are obtained using imbalanced biaxially oriented films prepared from films having a cast gauge of 4 to 15 mils which are reduced to the desired gauge by stretching, i.e., orientation.
The films are produced and oriented in a conventional manner. The film is heated to its orientation temperature and first subjected to MD orientation between two sets of nip rolls, the second rotating at a greater speed than the first in an amount equal to the desired draw ratio. Then the film is TD oriented by heating and subjecting it to transverse stretching in a tenter frame. Typically MD orientation is conducted at 60 to 120xc2x0 C. and TD orientation at 110 to 145xc2x0 C.
While it is preferred that the degree of orientation in a first film direction be at least three times less than the degree of orientation present in a direction substantially normal to the first direction, it is more particularly preferred that each HDPE film layer be oriented to an extent of about 1.1 to about 2.0 times in the machine direction (MD) and about 6 to about 12 times in the transverse direction (TD). It has been found that the HDPE film layers can be produced with excellent quality at caster speeds of up to about 110 feet per minute (fpm) corresponding to line speeds of 140 fpm at 1.25 times MD orientation. In the alternative, the degree of orientation in a first film direction can be at least three times greater than the degree of orientation present in a direction substantially normal to the first direction. Even unoriented blown HDPE may be used as the first and third layers and still maintain some degree of deadfold in the multilayer film substrate of the present invention.
When employed, this degree of imbalanced orientation produces an interesting effect in the HDPE components of the structure. The effect is a visible rippled and striated appearance, with the ripples being parallel to the transverse orientation direction. Under low magnification, in each square centimeter of HDPE film there will be seen from about 5 to about 30 discontinuous undulating ripples and striations generally parallel to the direction of orientation. This effect gives the film a slight translucent appearance, which tends to slightly blur distant objects viewed through the film. This effect indicates that the layers have been oriented in an imbalanced manner. The high density polyethylenes contemplated for use in the practice of the present invention include those disclosed in U.S. Pat. No. 4,870,122.
In the oriented polypropylene layer the orientation is adjusted to give essentially balanced tensile properties in both directions.
To achieve the desired surface characteristics required of the paper-like products of the present invention, one or more skin layers can be applied, in any known manner, to the multilayer HDPE substrate material, for example by coating or coextrusion before orientation or by coating the HDPE after one or both of the orientation operations. The skin layer can be any of the conventional materials used for this purpose in conjunction with polyolefin films, particularly polyethylene films. For example, to achieve a press-ready surface, a polymeric resin could be blended with fillers, fibers, pigments or the like, as necessary. Additionally, voided films, such as those disclosed in U.S. Pat. Nos. 4,377,616, 4,632,869, 4,758,462 and others, may be laminated to the multilayer HDPE substrate to impart the opacifying properties of those structures to the films of the present invention.
The HDPE-containing layers (a) and (c) as disclosed above can further comprise copolymer polypropylene skins, e.g., ethylene-propylene-butene-1 terpolymer, provided on at least one side thereof, preferably on both the inner and outer sides thereof. In one embodiment, the skins themselves can also comprise a component which is similar to components in the adhesive resin used to laminate layers (a), (b) and (c). For example, low density polyethylene (LDPE) can make up from 10 to 20 wt % of the skins, with the balance being a copolymer polypropylene.
A suitable adhesion-promoting primer which provides greater adhesion between the laminated surfaces, e.g., polymers selected from the group consisting of polyethyleneimide, epoxy, polyurethane, and acrylic, can be provided between the copolymer polypropylene skins (on the inner sides of (a) and (c)) and the laminating adhesive resin. Primer compositions are disclosed in U.S. Pat. Nos. 4,447,494 and 4,681,803, which are incorporated herein by reference.
It is also envisioned that the coated substrate can be embossed, dyed, printed, texturized or otherwise treated before or after lamination; this being done on the internal or external surfaces of the laminated layers, so as to provide, for example, visual and/or tactile identification of the nature of a banknote, its significance or value. Printing processes include, but are not limited to, lithography, UV-screen, flexography, gravure and intaglio printing processes. Any flexo or gravure printable ink, either colors or machine readable ink, such as lithographic, IR, UV, magnetic and intaglio inks, can be used. Printing on the core is also a security feature as well.
The opaque cavitated three-ply structure of the present invention can be surface-printed without losing opacity. This is a surprising result for intaglio processes which employ relatively high temperatures (greater than 70xc2x0 C.) and high pressures (greater than 1000 psi). Unlaminated cavitated films would generally have their cavitation crushed and lose opacity under similar conditions. The cavitation acts as a cushion that diminishes the abrasion force seen by the ink, making the ink more abrasion resistant.
The laminating techniques which can be employed to effect the present invention are known in the art and include: adhesive-bonding or cementing, e.g., with laminating adhesive resins, preferably with a transparent agent; solvent-bonding, where a mist of solvent is sprayed over the surfaces to be bonded together; thermal lamination by heat-bonding where thermoplastic sheets are subject to a hot rolling or pressing operation; cast-lamination where one layer is cast onto the second and the second forms a substrate; or, extrusion or draw-lamination as in calendering operations known in the art.
The use of solventless or 100% solids adhesive resins, such as a two-part polyurethane resin, WD4110, available from H.B. Fuller Co., is particularly preferred. 100% solids laminating adhesives are an effective alternative to solvent-based adhesives. 100% solids laminating adhesives impart excellent clarity, enhancement of printing, high bond strength and heat sealing resistance to the multilayer film laminated structure of the present invention.
When discrete security devices are incorporated within the substrate, e.g., optically-variable devices (OVD""s), they can be enclosed in pouches affixed to the substrate. On the other hand, the optically-variable devices themselves may be incorporated in one (or both) layers of the laminated substrate or between the layers, it not being necessary to incorporate a physically discrete device within a clearly defined pouch formed between the layers.
Any suitable security device can be employed in the present invention such as one selected from the group consisting of optically variable devices (OVDs), magnetic devices, electronic devices, and rare earth element-containing devices, with OVDs particularly preferred.
As employed in the present specification, the term xe2x80x9copticallyvariablexe2x80x9d is used to denote any device which can readily be made to change appearance in a reversible, predictable and reproducible manner. The appearance of such devices may be altered, for example, by the application of body-heat or manual pressure, the variation of the angle of viewing and, the lighting conditions under which viewing takes place. The type of devices envisioned by the present invention are: diffraction gratings, liquid crystals, moire patterns and similar patterns produced by cross-gratings with or without superimposed, refractive, lenticular and transparent grids, such as Fresnel lenses, spaced partially-reflective, and partially transparent, coatings yielding variable interference patterns or the like, bi-refringent or polarizing layers, zone-plates and the like.
Generally, optically-active devices of this nature are readily recognized by unskilled persons and are yet extremely difficult to reproduce by photographic and printing techniques. Moreover the production of any one such device in a reproducible fashion and the incorporation of such a device in a plastic laminate as described by the present invention is likely to be beyond the resources of the great majority of would-be forgers. Where a flexible paper-like product such as a banknote is sought, it is of course preferable that the optically-variable devices should, themselves, be sheet-like, flexible and thin; it is also preferable for such devices to be compatible with the plastic material employed for the laminae to facilitate bonding and mitigate against reactive changes occurring with time.
According to the present invention, one preferred form of optically variable device may be a reflecting diffraction grating consisting of a metallized thermoplastic film embossed with a diffraction pattern. To prevent access to the embossed pattern for the purpose of illicit replication, it is preferable according to the present invention to employ a layer of thermoplastic material on each side of the metallized film which has similar solubility characteristics to that of the metal layer so that separation by preferential etching will be rendered extremely difficult. Another preferred device is a moire pattern formed by photographically reproducing fine line or dot patterns on each side of a thin film. The spacings of the dots and lines can be readily made too fine to be reproduced by printing techniques and yet the moire pattern can be displayed upon a much larger scale. Unique diffraction and moire patterns will often be preferred for use in bank notes and techniques are available for producing those by computer and photo-reduction methods.
Security features can be incorporated into or onto the bank note, including reverse printing of the note to protect the security devices and the print.
It has been found that films similar to those of the present invention but which are xe2x80x9ccross-oriented,xe2x80x9d can be susceptible to curling at temperatures above 150xc2x0 F. Such cross-oriented films are similar to those of the present invention except that the second layer is laminated to the film substrate so that the first (primary) direction of orientation of the second layer is substantially normal to the first (primary) direction of orientation of the first layer. It is believed that such curling can result from differences in shrinkage at high temperatures in the machine direction and transverse direction of each layer. Additional curling susceptibility can result where coatings or skins of the layers have different coefficients of contraction from the HDPE component of the layers. Such imbalanced contraction and its attendant curling can be avoided by counterbalancing the overall shrinkage properties of one layer by laminating thereto a second layer identical to the first layer which is provided as a mirror image of the first layer. In other words, one half of the layered film structure is a mirror image of the other, with the plane of symmetry being along the horizontal midline of the layered film structure cross-section. This provides a cross-sectionally symmetrical layered film structure. Examples of such films include those of ABA, ABBA, ABCCBA, ABCDCBA, etc. construction where each letter represents a film layer, skin, coating, or adhesive layer. Such a cross-sectionally symmetrical layered film structure is necessarily a xe2x80x9cparallel-orientedxe2x80x9d structure, i.e., the primary direction of orientation of the first layer is parallel to the primary direction of orientation of the second layer in order to meet the mirror image requirement. Such a construction provides a symmetrical structure wherein the opposing shrinkage forces counteract each other to a significant degree. However, such a two layer parallel construction can be susceptible to poor tear properties in one direction, e.g, TD where two TD oriented films are employed.
It has now been found that using a low density polyethylene (LDPE) and/or a linear low density polyethylene (LLDPE) laminating resin oriented in the primary direction of orientation which is substantially perpendicular to the primary direction of orientation of the layers which it ties, evinces reduced susceptibility to tearing. The laminating resin can itself be subjected to orienting to some extent during lamination, preferably after the resin has at least partially or completely solidified, and preferably in the machine direction. Such orienting can be from 1.5 to 10 times, preferably from 4 to 6 times, corresponding to a total drawdown of the laminating adhesive resin of greater than 10%, preferably greater than 20%, say, 75%.
It has also been found that by using a 100% solids resin as the laminating adhesive resin employed, orientation effects resulting from the lamination procedure are improved, resulting in a multilayer film exhibiting curt resistance and improved chemical resistance.
One or both of the HDPE containing layers may be weakened in terms of tear resistance in one direction to a point where they are significantly weaker than the laminating adhesive resin and the OPP containing core layer. When attempting to delaminate the structure for counterfeiting purposes, only small strips of the outer printed HDPE containing layers would be removed. The entire HDPE containing layers would not be removable.
The HDPE containing layer can be tear weakened using process conditions during manufacture. Microperforating with laser technology and/or nicking will also cause the HDPE containing layers to weaken. The microperforations are either diagonal or unidirectional, e.g. in the range of from about 50 to about 300 dots per inch (dpi).
The HDPE layers can also be tear weakened through the addition of incompatible additives that would cause the layer to fibrilate or fracture during orientation. Suitable incompatible polymer additives which effect crystallization include polyester (PET), polybutylene terephthalate (PBT), polystyrene or a mixture thereof. Generally, from about 1 to about 10 wt. %, preferably from about 4 to about 8 wt. % of incompatible additive is added to the HDPE layer(s). Fibrillation results in regions of oriented HDPE surrounding long, planar regions of the incompatible polymer resulting in low tear regions.
The OPP core layer is not weakened and essentially provides the tensile properties and tear resistance of the structure as a whole.
The invention is further illustrated by the following non-limiting examples.

Multilayer structure containing cavitated materials for use in the production of security documents


A pre-provisioned application platform may be provided. First, a plurality of parameters may be received. Then a plurality of pre-provisioned tenants may be created based upon the received plurality of parameters. A request for service may be received and then an actual tenant may be assigned to one of the plurality of pre-provisioned tenants in response to the received request.

Cloud computing provides computation, software, data access, and storage services that do not require end-user knowledge of the physical location and configuration of the system that delivers the services. Parallels to this concept can be drawn with the electricity grid, wherein end-users consume power without needing to understand the component devices or infrastructure required to provide the service.
Cloud computing describes a new supplement, consumption, and delivery model for IT services based on Internet protocols, and it typically involves provisioning of dynamically scalable and often virtualized resources. It is a byproduct and consequence of the ease-of-access to remote computing sites provided by the Internet. This may take the form of web-based tools or applications that users can access and use through a web browser as if the programs were installed locally on their own computers.

Pre-provisioned web application platform site collections


A storage caddy has a slidable drawer on which items are stored. Items are presented for removal when the drawer is slid from the shell of the caddy. Items stored in a caddy with a hinged drawer, can be removed by breaking the drawer at the hinge to drop the item toward the ground for convenient and safe removal. A set of golf clubs stored in the caddy in the bed of a pick-up truck are slid from the shell on the drawer. The horizontal plane of the drawer is then broken at the hinge and the bottom of the golf bag moves toward the ground. The golf bag can then be easily lifted onto the shoulder or rolled away. The caddy positions heavy items for easy removal preventing undue stress or injury on those retrieving items from the caddy.

Golf is a sport that can be enjoyed by almost everyone. Carrying and transporting a golf bag loaded with heavy clubs, however, can be burdensome for some golfers. A golf bag with wheels prevents the golfer from having to carry the loaded bag over a shoulder, but the bag still must be lifted from the ground into or out of the trunk of a car, or the back of a vehicle. Placing golf clubs in the bed of a pick-up truck requires that the bag be either hoisted over the sides of the bed or at least lifted to the level of an open tailgate. A golf bag stored in the trunk of a car or the back of a van or sports utility vehicle (SUV) requires one to reach into the vehicle to remove it lifting with the back instead of properly lifting with the legs. A means by which a golf bag, or any heavy object, can be loaded into a vehicle, especially into the bed of a pick-up truck, without having to lift the object from the ground into the vehicle would prevent undue stress on bones, joints and muscles. Further, a means by which a golf bag can be presented to the golfer without the golfer having to reach into the vehicle and lift improperly can reduce back strain. Finally, perhaps such a means could also make accessible a sport or activity that may be restricted to those who are limited physically.
Storage racks and tool trays that fit into the bed of a pick-up have been described (U.S. Pat. Nos. 6,006,971 and 6,253,976 B1). Often these tool racks incorporate drawers that slide out of the bed of the truck (U.S. Pat. Nos. 4,915,437, 5,848,694 and U.S. Pat. No. 5,897,154). These references do not however describe a storage unit for a pick-up that lowers a stored object to the ground for easy removal. Likewise, various golf bag storage devices which have been described for storing golf bags in or on golf carts (U.S. Pat. No. 5,788,070) or in mini-vans or sport utility vehicles (U.S. Pat. No. 6,276,583 B1) require that the bag be lifted out of the storage device.
The need remains for a storage device which presents a stored item to a user and/or lowers the stored item, such as a golf bag, from the vehicle in which it is stored to the ground to prevent one from having to lift the item into and out of the vehicle. Since tools and sporting equipment, especially golf clubs, are expensive, it would be an added advantage if this storage device, or caddy, is lockable and secure.
All patents, patent applications, provisional patent applications and publications referred to or cited herein, are incorporated by reference in their entirety to the extent they are not inconsistent with the explicit teachings of the specification.
The subject invention involves a storage caddy with a slidable drawer that positions items for convenient removal. A hinged drawer in the caddy allows an item to be lowered to the ground for easy, safe removal. The storage caddy of the subject invention has an outer shell which slidably receives the tray or drawer. A preferred embodiment of the caddy is used for securing and storing golf bags in the bed of a pick-up truck. A golf bag laid on a hinged drawer can be secured within the lockable shell which is bolted to the truck bed. To remove the golf bag from the storage caddy, the drawer is slid from the shell, presenting the bag to the golfer. To further facilitate removal of the bag from the truck, the drawer can be broken at the hinge. The end of the bag on the broken drawer moves toward the ground, thus it is not necessary to awkwardly lift the bag from the bed of the pick-up. The caddy of the subject invention is useful for those with limited mobility and can prevent muscle strain or joint injury. Further, the shell and the drawer of the storage caddy of the subject invention can be lockably engaged to provide a secure storage area.


An inventory control and management method provides a combination mobile device for communication and for reading labels (RandC). The RandC reads an inventory label affixed to an item of inventory in the stores. A data file is created corresponding to the label reading and includes a time stamp taken at the time of the reading. The data file is imported into a computer data processor. A network of fixed distributed communication nodes (transceivers) is positioned over the inventory store for receiving temporal cyclic signature pulses from the RandC. At least three of the communication nodes are used to perform a triangulation for locating the RandC, and the location and the corresponding time is recorded. By comparing the time of a given reading of the label with a corresponding time of the triangulation, it is possible to determine where any item is located within the stores.

Applicant(s) hereby incorporate herein by reference, any and all U. S. patents, U.S. patent applications, and other documents and printed matter cited or referred to in this application.
1. Field of the Invention
This invention relates generally to inventory systems and more particularly to such a system capable of locating items of inventory in a three-space environment.
2. Description of Related Art
The following art defines the present state of this field:
Barritz et al., U.S. 20020008621 describes a system and method, which allows the identity of assets and their physical locations to be mapped and associated with one another. The invention includes a locator tool which receives an input which allows the tool to determine its own spatial location and thereby the spatial locations of various objects such as furniture, computer equipment, and structural components such as doors, windows to be identified and located and thereafter mapped in the form of architectural layout, diagrams, and the like. The invention is also an inventory system as well as a verification system that allows objects or assets to be inventoried, tracked, or verified against purchasing lists or the like.
Stanis et al., U.S. Pat. No. 4,135,241 describes a data handling system for a hospital or like establishment. The system keeps track of bed allocation, changes in inventory, and charges to patients, and also serves as a communication network for the hospital. Data is fed into the system in the form of pre-punched cards bearing patient information, inventory data, and commands or messages, and thus unskilled personnel can quickly feed data into the system without error. Message data is routed directly to teleprinters at addressed locations. Bed allocation and patient data, and charge and inventory data are respectively stored in separate magnetic drum storage areas. Searching facilities are provided which can locate desired data entries in either storage area and mark these entries for printout, and separate printout circuitry then transfers marked data items to the proper addresses in the proper format. At the end of each day, a final search is performed which produces a printout of all charges organized by patient number. A tally inventory search is also performed which produces a printout of inventory changes organized by item number and by department number. The tally search is cumulative, and a tally arithmetic unit summarizes inventory data for each separate item before printout. A running record is kept of each day""s total charges, credits, and payments on account in a central core memory, and this record is continually updated by a central arithmetic unit.
Guthrie, U.S. Pat. No. 5,565,858 describes a device, which locates a container from a group of containers utilizing an electronic tag; the electronic tag is capable of being positioned in close proximity to one of the containers. The electronic tag includes at least one long-range transceiver portion and at least one short-range transceiver portion. Each long-range transceiver portion is capable of communicating with either a short-range transceiver portion associated with another electronic tag, or an interrogator unit. Each short-range transceiver portion is capable of communicating with a long-range transceiver portion of another electronic tag. The device assists in locating a container, relative to other containers, when the containers are stored in a stacked or nested configuration. A global positioning system (GPS) can be utilized to locate the position of the containers on the Earth""s surface.
Bunte et al., U.S. Pat. No. 5,873,070 describes an improved data collection system utilizing at least partially integrated data collection and gathering devices and related peripherals. The system includes an at least partially wearable data collection terminal, associated peripherals, and a communication system. The data collection system may utilize a wearable data collection terminal having a computer processor, associated memory, inputs, and outputs. Associated peripheral devices may include voice inputs and outputs; an optically readable information set reader, a keyboard and/or touch-panel, intelligent-body-conforming battery packs, mass storage devices, user position and next task location device, a display, a printer, and a data communication system for both local area and wide area communication.
Woolley, U.S. U.S. Pat. No. 5,959,568 describes an object in a storage area or moving vehicle that is monitored by attaching an electronic tag to the object. An electronic device detects the presence of the object by communicating with the tag while the object is in storage or is being moved by the vehicle. The tags may also determine the location of an attached object and may reroute the object if it deviates from a given shipping schedule. A group of objects is monitored by two electronic tags, each attached to an object in the group. Each tag has circuitry for communicating information relating to an object in the group to a second tag. Each tag also includes a memory connected to the circuitry that is capable of storing the information, and a controller connected to the memory and the circuitry. A distance is measured by transmitting multiple symbols from one object to another object, having the symbols returned such that the symbols"" measured round-trip times are not all identical, and calculating the distance using the measured round-trip times.
Amon et al., U.S. Pat. No. 5,960,413 describes a scanning radar unit or a phased array scanning radar unit, for the purposes of additionally obtaining unit interior topological information. Such interior information is required to determine an accurate tally count in the case where two or three boards such as, have been longitudinally aligned to span the entire board row of a given coarse (a technique referred to as xe2x80x9cnestingxe2x80x9d). In the case of scanning radar unit, this additional interior topology information is gathered by emitting a focused pulsed incident scanning energy beam, which is of an energy chosen to be transmissive to paper wrap materials which might be covering unit and to the lumber of unit itself. As beam transmits through xe2x80x9cnestedxe2x80x9d boards such as it will encounter a board row break such as where the two boards are abutted. Either board end, which defines this break, will have been previously demarcated during unit construction by a reflective material. This reflective marking will cause the incident beam to reflect back towards scanning radar unit as reflective beam. The reflective information obtained by unit is input to the unit interior topological processor which then determines the three dimensional locations of all board row breaks within lumber unit which is communicated to computer. Computer then combines this interior end surface information with the exterior information to provide a precise tally count of unit.
O""Callaghan et al., U.S. Pat. No. 6,311,892 describes Apparatus for automatically acquiring and verifying, relative to pre-established rules, information affixed to relatively flat articles transported along a transport path comprises weighing means for measuring weight of articles being processed, image acquisition means for acquiring a representation of indicia appearing on an article, processing means for recognition of the indicia appearing on an article, and processing means for verifying acquired data against the pre-established rules.
Salvo et al., U.S. Pat. No. 6,341,271 describes an inventory management system that automatically monitors inventory amounts, provides information concerning inventory, and decides if an order for replacement inventory should be placed. The system includes a storage for inventory, an indicator for monitoring and reporting the level of current inventory, and a controller for receiving information from different inventory suppliers and for integrating such information with information on current inventory amounts and estimated future use to decide if an order for replacing inventory should be made. An order is placed automatically to a supplier and the progress for the delivery of replacement inventory is automatically monitored. A method using this system for managing inventory includes the steps of automatic gathering information about the current inventory and deciding whether and when replacement inventory should be ordered.
Barnett, U.S. Pat. No. 6,343,276 describes a shoe size scanner system that is an automated system for use in retail stores, and particularly in shoe stores. The scanner system has a base unit which interfaces with the store""s computerized inventory system, and a plurality of remote units, which interface with the base unit. The remote units include at least the input device of a bar code scanner, and may be either fixed mount or portable, handheld scanning units. The fixed mount units are positioned in fixed locations, such as display shelves or tables and may be used by either store clerks or customers. The handheld units are intended for use by sales clerks, and may be supported by a neck strap, armband, or belt clip. According to the shoe size scanner system, each shoe on display in the store has a bar code affixed thereto which encodes an identifier number corresponding to the model of the shoe. Either a sales clerk or a customer may scan the bar code with the remote unit, which communicates with the base unit and returns identification of the shoe model. The sales clerk or customer may then select one of three function keys so that the remote unit will display, for that particular model, either (1) a list of all shoe sizes in stock; (2) a response indicating whether the shoe is in stock in a specified length and width; or (3) a list of all shoe widths in stock in a specified length. Price information for each shoe listed in the response is provided.
Engellenner, U.S. Pat. No. 6,388,569 describes a method and apparatus for location of objects to facilitate retrieval, filing, security, inventory stock-keeping and the like. The methods and apparatus employ a tag element associated with each object-to-be-located, and interrogation system for searching one or more spatial regions for such tagged items, as well as mechanisms for identifying objects within the interrogated region.
Norand Corporation, WO94/10774 describes an apparatus for a radio communication network having a multiplicity of mobile transceiver units selectively in communication with a plurality of base transceiver units which communicate with one or two host computers for storage and manipulation of data collected by bar code scanners or other collection means associated with the mobile transceiver units. The radio network is adaptive in that in order to compensate for the wide range of operating conditions a set of variable network parameters are exchanged between transceivers in the network. These parameters define optimized communication on the network under current network conditions. Examples of such parameters include: the length and frequency of the spreading code in direct-sequence spread spectrum communications; the hop frame length, coding, and interleaving in frequency-hopping spread spectrum communications; the method of source encoding used; and the data packet size in a network using data segmentation.
Creative Golf Designs, Inc., WO 0077704 describes an inventory control system, which includes anti-collision, radio frequency identification apparatus or tags affixed to each item of an inventory and including a unique modulation code, an interrogator/reader that generates a field of sufficient range to activate each tag associated with each item of the inventory in communication with a computer. The computer includes a list comprising an identifier for each item in the inventory, the modulation code for the tag associated with each item in the inventory and an item status where the status indicates whether the item is present or absent.
The prior art teaches systems for: locating inventory, inventory management and control, stacked containers, data collection, measuring distance, portable identification and classification, verification, scanning shoes, electronic location, and for applying adaptive communication parameters, but does not teach a system for locating items of inventory in three-space in an inexpensive and adaptive manner. The present invention fulfills these needs and provides further related advantages as described in the following summary.
The present invention teaches certain benefits in construction and use which give rise to the objectives described below.
The present invention is an inventory control and management method for use in large inventory stores such as warehouses containing thousands of items. Such items may be of any type, such as automobiles, tires, hardware, tools, foodstuffs, and so on, and may be stored in a two-dimensional array, such as with automobiles on a sales lot, or in a three-dimensional array (in three-space) such as in aisles and racks. In modern warehouses, such racks may be tens of feet in height and it is important to determine where small items are in a warehouse that may consume a square city block or more, and be 20 to 30 feet in height.
To accomplish the inventory control and management method of the present invention provides a combination mobile device for reading labels and for communication (RandC). The RandC is used in an inventory stores. It is positioned for reading an inventory label affixed to an item of inventory in the store. A data file is created corresponding to the label reading and includes a time stamp taken at the time of the reading. The data file is transmitted using radio transmission from the RandC to a receiver and is then imported into a computer data processor. A network of fixed distributed communication nodes (transceivers) is positioned over the inventory store for receiving temporal cyclic signature pulses from the RandC which are transmitted constantly. At least three of the communication nodes within communication range, at any time, of the RandC are used to preform a triangulation for locating the RandC, and the location of the RandC in three space is recorded. A corresponding time for each one of the signature pulses is likewise recorded. In this manner a record of the location of the RandC is maintained constantly, and by comparing the time of a given reading of the label with a corresponding time of the triangulation of the location of the RandC, it is possible to determine where any item is located within the stores.
A primary objective of the present invention is to provide an apparatus and method of use of such apparatus that provides advantages not taught by the prior art.
Another objective is to provide such an invention capable of recording the nature and location in three-space, of items in an inventory stores.
A further objective is to provide such an invention capable of high accuracy in locating items so that the method may be used with small items.
A still further objective is to provide such an invention capable of keeping a record of the movements of plural information retrieving devices in a large inventory stores such as a warehouse.

System for cataloging an inventory and method of use


Nonwoven filaments having improved melt spinning process characteristics and end use properties are prepared using a visbroken single-site catalyzed propylene polymer. The propylene polymer has a first melt flow rate (MFR) before visbreaking and a second MFR after visbreaking, such that the ratio of the second MFR to the first MFR is about 1:1 to about 3:1. The nonwoven filaments exhibit less filament tension during spinning, and permit higher line speeds before breaking, than similar filaments prepared using a single-site catalyzed propylene polymer having the second MFR straight out of the reactor, and which has not been visbroken.

This invention relates to nonwoven fibers and fabrics prepared using visbroken single-site catalyzed polypropylene, wherein the ratio of the melt flow rate (MFR) of the polypropylene after visbreaking to its MFR before visbreaking is from about 1:1 to about 3:1.
Conventional, Ziegler-Natta catalyzed polypropylenes have a relatively broad molecular weight distribution after leaving the reactor. It has long been known to partially degrade or xe2x80x9cvisbreakxe2x80x9d propylene homopolymers and copolymers to narrow the molecular weight distributions. Visbreaking processes are disclosed, for instance, in U.S. Pat. No. 4,282,076, issued to Boynton et al. and U.S. Pat. No. 5,250,631, issued to McCullough, Jr., et al. Visbreaking techniques involve thermal degradation, radiation, and the use of peroxides and other catalysts. Visbreaking of conventional polypropylenes leads to narrower molecular weight distributions (as well as lower average molecular weights) because initially larger polypropylene molecules are more susceptible to visbreaking than initially smaller polypropylene molecules. U.S. Pat. No. 5,723,217 issued to Stahlet al., discloses that the melt spinning of conventional (Ziegler-Natta catalyzed) propylene polymers improves with the degradation of the polymers using peroxide. Stahl et al. further discloses the melt spinning of propylene polymers prepared using single-site metallocene-type catalysts. According to Stahl et al., reactor-grade (i.e. non-visbroken) single-site catalyzed propylene polymers provide the same fiber spinning advantages as visbroken Ziegler-Natta propylene polymers, because the single-site polymers have narrower molecular weight distributions leaving the reactor. These advantages include, for instance, better ease of processing and the ability to make small diameter, high strength fibers. Thus, the use of a metallocene catalyzed propylene polymer eliminates the need for a visbreaking process step.
Stahl et al. further discloses that metallocene catalyzed propylene polymers can be visbroken to a lower molecular weight to facilitate fiber production. Stahl et al. alleges that the visbreaking does not change the molecular weight distribution, defined as the ratio of weight average molecular weight to number average molecular weight. From the disclosure of Stahl et al., for instance, it would appear that a reactor grade 5 MFR polymer which is visbroken to 55 MFR, results in a polymer having the same narrow molecular weight distribution as before. For purposes of melt spinning, there is no apparent incentive to visbreak a lower MFR metallocene polymer to a higher MFR, as opposed to melt spinning a higher MFR reactor grade metallocene polymer which has not been visbroken.
It has been discovered, unexpectedly, that a single-site catalyzed propylene polymer visbroken to a higher MFR from a lower MFR exhibits better melt spinning properties than a similar single-site catalyzed reactor grade propylene polymer initially having the higher MFR, when the ratio of the higher MFR to the lower MFR is about 1:1 to about 3:1. Thus, contrary to the teachings of the prior art, there is an advantage to visbreaking a lower MFR single-site catalyzed propylene polymer to a higher MFR, instead of simply producing the higher MFR polymer in a polymerization reactor.
The present invention is directed to nonwoven fibers which are spun from a metallocene catalyzed propylene polymer which has been visbroken from a lower MFR to a higher MFR, wherein the ratio of the higher MFR to the lower MFR is about 1:1 to about 3:1. The present invention is also directed to nonwoven fabrics produced from the fibers, and to personal care and medical products that include the nonwoven fabrics.
It is a feature and advantage of the invention to provide a relatively strong, thin fiber made from a single-site catalyzed propylene polymer visbroken from a lower MFR to a higher MFR, and which may be thinner (finer) than would be produced under similar conditions using a reactor grade single-site propylene polymer having the higher MFR.
It is also a feature and advantage of the invention to produce a nonwoven web of fibers made using the visbroken single-site catalyzed propylene polymer, and various personal care and medical products incorporating the nonwoven web.
The term xe2x80x9cnonwoven fabric or webxe2x80x9d means a web having a structure of individual fibers or threads which are interlaid, but not in a regular or identifiable manner as in a knitted fabric. Nonwoven fabrics or webs have been formed from many processes such as, for example, meltblowing processes, spunbonding processes, air laying processes, and bonded carded web processes. The basis weight of nonwoven fabrics is usually expressed in ounces of material per square yard (osy) or grams per square meter (gsm) and the fiber diameters are usually expressed in microns. (Note that to convert from osy to gsm, multiply osy by 33.91.) The term xe2x80x9cmicrofibersxe2x80x9d means small diameter fibers having an average diameter not greater than about 75 microns, for example, having an average diameter of from about 7 microns to about 30 microns. Another frequently used expression of fiber diameter is denier, which is defined as grams per 9000 meters of a fiber. For a fiber having circular cross-section, denier may be calculated as fiber diameter in microns squared, multiplied by the density in grams/cc, multiplied by 0.00707. A lower denier indicates a finer fiber and a higher denier indicates a thicker or heavier fiber. For example, the diameter of a polypropylene fiber given as 15 microns may be converted to denier by squaring, multiplying the result by 0.89 g/cc and multiplying by .00707. Thus, a 15 micron polypropylene fiber has a denier of about 1.42 calculated as (152xc3x970.89xc3x97.00707 =1.415). Outside the United States the unit of measurement is more commonly the xe2x80x9ctex,xe2x80x9d which is defined as the grams per kilometer of fiber. Tex may be calculated as denier /9.
The term xe2x80x9cspunbonded fibersxe2x80x9d refers to small diameter fibers which are formed by extruding molten thermoplastic material as filaments from a plurality of fine capillaries of a spinneret having a circular or other configuration, with the diameter of the extruded filaments then being rapidly reduced as by, for example, in U.S. Pat. No. 4,340,563 to Appel et al., and U.S. Pat. No. 3,692,618 to Dorschner et al., U.S. Pat. No. 3,802,817 to Matsuki et al., U.S. Pat. Nos. 3,338,992 and 3,341,394 to Kinney, U.S. Pat. No. 3,502,763 to Hartman, U.S. Pat. No. 3,502,538 to Petersen, and U.S. Pat. No. 3,542,615 to Dobo et al., each of which is incorporated herein in its entirety by reference. Spunbond fibers are quenched and generally not tacky when they are deposited onto a collecting surface. Spunbond fibers are generally continuous and often have average diameters larger than about 7 microns, more generally, between about 10 and 75 microns.
The term xe2x80x9cmeltblown fibersxe2x80x9d means fibers formed by extruding a molten thermoplastic material through a plurality of fine, usually circular, die capillaries as molten threads or filaments into converging high velocity heated gas (e.g., air) streams which attenuate the filaments of molten thermoplastic material to reduce their diameter, which may be to microfiber diameter. Thereafter, the meltblown fibers are carried by the high velocity gas stream and are deposited on a collecting surface to form a web of randomly dispersed meltblown fibers. Such a process is disclosed for example, in U.S. Pat. No. 3,849,241 to Butin. Meltblown fibers are microfibers which may be continuous or discontinuous, are generally smaller than 10 microns in diameter, and are generally self bonding when deposited onto a collecting surface. Meltblown fibers used in the present invention are preferably substantially continuous in length.
The term xe2x80x9cmonocomponentxe2x80x9d fibers refers to fibers formed from one or more extruders using only one polymer. This is not meant to exclude fibers formed from one polymer to which small amounts of additives have been added for color, anti-static properties, lubrication, hydrophilicity, etc. These additives, e.g., titanium dioxide for color, are generally present in an amount less than 5 weight percent and more typically about 2 weight percent.
The term xe2x80x9cbicomponent filaments or fibersxe2x80x9d refers to fibers which have been formed from at least two polymers extruded from separate extruders but spun together to form one fiber. The polymers are arranged in substantially constantly positioned distinct zones across the cross-section of the bicomponent fibers and extend continuously along the length of the bicomponent fibers. The configuration of such a bicomponent fiber may be, for example, a sheath/core arrangement wherein one polymer is surrounded by another or may be a side-by-side arrangement or an xe2x80x9cislands-in-the-seaxe2x80x9d arrangement. Bicomponent fibers are taught in U.S. Pat. No. 5,108,820 to Kaneko et al., U.S. Pat. No. 5,336,552 to Strack et al., and U.S. Pat. No. 5,382,400 to Pike et al., each of which is incorporated herein in its entirety by reference. For two component fibers, the polymers may be present in ratios of 75/25, 50/50, 25/75 or any other desired ratios. Conventional additives, such as pigments and surfactants, may be incorporated into one or both polymer streams, or applied to the filament surfaces.
The term xe2x80x9cbiconstituent fibersxe2x80x9d refers to fibers which have been formed from at least two polymers extruded from the same extruder as a blend. The term xe2x80x9cblendxe2x80x9d is defined below. Biconstituent fibers do not have the various polymer components arranged in relatively constantly positioned distinct zones across the cross-sectional area of the fiber and the various polymers are usually not continuous along the entire length of the fiber, instead usually forming fibrils or protofibrils which start and end at random. Biconstituent fibers are sometimes also referred to as multiconstituent fibers. Fibers of this general type are discussed in, for example, U.S. Pat. No. 5,108,827 to Gessner. Bicomponent and biconstituent fibers are also discussed in the textbook Polymer Blends and Composites by John A. Manson and Leslie H. Sperling, copyright 1976 by Plenum Press, a division of Plenum Publishing Corporation of New York, ISBN 0-306-30831-2, at Pages 273 through 277.
The term xe2x80x9cblendxe2x80x9d as applied to polymers, means a mixture of two or more polymers while the term xe2x80x9calloyxe2x80x9d means a sub-class of blends wherein the components are immiscible but have been compatibilized.
The term xe2x80x9cpolymerxe2x80x9d includes, but is not limited to, homopolymers, copolymers, such as for example, block, graft, random and alternating copolymers, terpolymers, etc. and blends and modifications thereof Furthermore, unless otherwise specifically limited, the term xe2x80x9cpolymerxe2x80x9d shall include all possible geometrical configurations of the material. These configurations include, but are not limited to isotactic, syndiotactic and atactic symmetries.
The term xe2x80x9cpropylene polymerxe2x80x9d includes both propylene homopolymers and copolymers. Especially useful are polymers containing a preponderance of propylene, such as homopolymers and copolymers containing about 90-100% by weight propylene and about 0-10% by weight of ethylene or 0-50% by weight of a C4-C20 alpha-olefin comonomer. Propylene homopolymers and random copolymers are especially preferred.
The term xe2x80x9csingle site catalyzedxe2x80x9d propylene polymers include propylene polymers and copolymers produced by single-site catalysis, including without limitation metallocene catalyzed propylene homopolymers and copolymers. The metallocene process for making polyolefins uses a metallocene catalyst which is activated (i.e. ionized) by a co-catalyst.
Polymers produced using metallocene catalysts have a narrow molecular weight distribution. xe2x80x9cNarrow molecular weight distribution polymerxe2x80x9d refers to a polymer that exhibits a molecular weight distribution of less than about 3.5. As is known in the art, the molecular weight distribution of a polymer is the ratio of the weight average molecular weight of the polymer to the number average molecular weight of the polymer. Methods of determining molecular weight distribution are described in the Encyclopedia of Polymer Science and Engineering, Volume 3, Pages 299-300 (1985). Examples of narrow molecular weight distribution polyolefins include metallocene-catalyzed polyolefins, constrained geometry-catalyzed polyolefins, and other single-site catalyzed polyolefins, described above. Polydispersities (Mw/Mn) of below 3.5 and even below 2 are possible for metallocene produced polymers. These polymers also have a narrow short chain branching distribution when compared to similar Ziegler-Natta produced polymers.
Metallocene catalysts include bis(n-butylcyclopentadienyl) titanium dichloride, bis(n-butylcyclopentadienyl)zirconium dichloride, bis(cyclopentadienyl)-scandium chloride, bis(indenyl)zirconium dichloride, bis(methylcyclopentadienyl)-titanium dichloride, bis(methylcyclopentadienyl)zirconium dichloride, cobaltocene, cyclopentadienyltitanium trichloride, ferrocene, hafnocene dichloride, isopropyl-(cyclopentadienyl1-1-flourenyl)zirconium dichloride, molybdocene dichloride, nickelocene, niobocene dichloride, ruthenocene, titanocene dichloride, zirconocene chloride hydride, zirconocene dichloride, among others. A more exhaustive list of such compounds is included in U.S. Pat. No. 5,374,696 to Rosen et al. and assigned to the Dow Chemical Company. Such compounds are also discussed in U.S. Pat. No. 5,064,802 to Stevens et al. and also assigned to Dow.
The metallocene process, and particularly the catalysts and catalyst support systems are the subject of a number of patents. U.S. Pat. No. 4,542,199 to Kaminsky et al. describes a procedure wherein a metallocene catalyst of the general formula (cyclopentadienyl)2MeRHal wherein Me is a transition metal, Hal is a halogen and R is cyclopentadienyl or a C1 to C6 alkyl radical or a halogen, is used to form polyethylene. U.S. Pat. No. 5,189,192 to LaPointe et al. and assigned to Dow Chemical describes a process for preparing addition polymerization catalysts via metal center oxidation. U.S. Pat. No. 5,352,749 to Exxon Chemical Patents, Inc. describes a method for polymerizing monomers in fluidized beds. U.S. Pat. No. 5,349,100 describes chiral metallocene compounds and preparation thereof by creation of a chiral center by enantioselective hydride transfer.
Co-catalysts are materials such as methylaluminoxane (MAO) which is the most common, other alkylaluminums and boron containing compounds like tris(pentafluorophenyl)boron, lithium tetrakis(pentafluorophenyl)boron, and dimethylanilinium tetrakis(pentafluorophenyl)boron. Research is continuing on other co-catalyst systems or the possibility of minimizing or even eliminating the alkylaluminums because of handling and product contamination issues. The important pont is that the metallocene catalyst be activated or ionized to a cationic form for reaction with the monomer(s) to be polymerized.
It is also possible using a metallocene catalyst system to control the isotacticity of the polymer quite closely when stereo selective metallocene catalysts are employed. In fact, polymers have been produced having an isotacticity in excess of 99 percent. It is also possible to produce highly syndiotactic polypropylene using this system.
Controlling the isotacticity of a polymer can also result in the production of a polymer which contains blocks of isotactic and blocks of atactic material alternating over the length of the polymer chain. This construction results in an elastic polymer by virtue of the atactic portion. Such polymer synthesis is discussed in the journal Science, Volume 267 (Jan. 13, 1995) at Page 191 in an article by K. B. Wagner. Wagner, in discussing the work of Coates and Waymouth, explains that the catalyst oscillates between the stereochemical forms resulting in a polymer chain having running lengths of isotactic stereocenters connected to running lengths of atactic centers. Isotactic dominance is reduced producing elasticity. Geoffrey W. Coates and Robert M. Waymouth, in an article entitled xe2x80x9cOscillating Stereocontrol: A Strategy for the Synthesis of Thermoplastic Elastomeric Polypropylenexe2x80x9d at Page 217 in the same issue, discuss their work in which they used metallocene bis(2-phenylindenyl)-zirconium dichloride in the presence of methylaluminoxane (MAO), and, by varying the pressure and temperature in the reactor, oscillate the polymer form between isotactic and atactic.
Commercial production of metallocene polymers is somewhat limited but growing. Such polymers are available from Exxon Chemical Company of Baytown, Texas under the trade name ACHIEVE(copyright) for polypropylene based polymers and EXACTS(copyright) for polyethylene based polymers. Dow chemical company of Midland, Michigan has polymers commercially available under the name ENGAGE(copyright). These materials are believed to be produced using non-stereo selective metallocene catalysts. Exxon generally refers to their metallocene catalyst technology as xe2x80x9csingle sitexe2x80x9d catalysts while Dow refers to theirs as xe2x80x9cconstrained geometryxe2x80x9d catalysts under the name INSIGHT(copyright) to distinguish them from traditional Ziegler-Natta catalysts which have multiple reaction sites. Other manufacturers such as Fina Oil, BASF, Amoco, Hoechst and Mobil are active in this area and it is believed that the availability of polymers produced according to this technology will grow substantially in the next decade.
The term xe2x80x9creactor gradexe2x80x9d refers to a propylene polymer which has not been visbroken, i.e., has not been subjected to a molecular degradation process, after its initial production in a polymerization reactor. The term xe2x80x9creactor gradexe2x80x9d is intended to exclude polymers which have been visbroken to lower their initial molecular weight, and/or to alter their initial molecular weight distribution.
The term xe2x80x9csubstantially continuous filaments or fibersxe2x80x9d refers to filaments or fibers prepared by extrusion from a spinneret, including without limitation spunbonded and meltblown fibers, which are not cut from their original length prior to being formed into a nonwoven web or fabric. Substantially continuous filaments or fibers may have lengths ranging from greater than about 15 cm to more than one meter; and up to or beyond the length of the web or fabric being formed. The definition of xe2x80x9csubstantially continuous filaments or fibersxe2x80x9d includes those which are not cut prior to being formed into a nonwoven web or fabric, but which are later cut when the nonwoven web or fabric is cut.
The term xe2x80x9cstaple fibersxe2x80x9d means shorter fibers which are natural or cut from a manufactured filament prior to forming into a web, and which have an average length ranging from about 0.1-15 cm, more commonly about 0.2-7 cm.
The term xe2x80x9csticking pointxe2x80x9d of fibers extruded from a spinneret refers to the maximum fiber distance, measured from the face of the spinneret, where a metal rod placed in contact with the fibers will stick to them. A circular aluminum rod having a 0.5 inch diameter is placed adjacent to the fibers at a large distance from the spinneret, and is gradually moved along the adjacent fiber surfaces in a direction approaching the spinneret. When the fibers begin sticking to the rod, the distance from the rod to the spinneret is recorded as the sticking point.
The term xe2x80x9cfiber tenacityxe2x80x9d refers to a measurement made in accordance with ASTM D3822, modified to the extent that 72 filaments (instead of one) are tested using a Textechno Statiomat M measuring device. The gauge length used is 100 mm, the test speed is 1270 mm/min, and the pre-tension is set at 0.5 centinewtons per text. The standard test procedure is otherwise followed.
The term xe2x80x9cpersonal care productxe2x80x9d includes diapers, training pants, swim wear, absorbent underpants, baby wipes, adult incontinence products, and feminine hygiene products, and the like, as well as other surge and intake material products.
The term xe2x80x9cmedical care productxe2x80x9d includes medical garments, underpads, absorbent drapes, bandages, medical wipes, and the like.
The starting material for the invention is a single-site catalyzed propylene polymer, which may be a homopolymer or any of the copolymers indicated above. Preferred propylene polymers include homopolymers and copolymers containing up to about 10% by weight of ethylene or up to about 50% by weight of a C4-C20 alpha-olefin comonomer. The ethylene content should be limited because some of the visbreaking processes which advantageously affect polypropylene, may cause gelling, crosslinking and other less desirable reactions in polyethylene-type materials. Thus, it is preferred that any ethylene comonomer be present at a low level. Propylene homopolymers and random copolymers are preferred over block copolymers, for similar reasons. Isotactic propylene homopolymers and copolymers are generally preferred over atactic and syndiotactic materials, although combinations of different stereoisomers may be advantageous in some circumstances.
The starting propylene polymer may be a reactor grade single-site catalyzed material. For instance, the starting material may be a reactor grade metallocene-catalyzed propylene polymer, or a reactor grade constrained geometry-catalyzed propylene polymer. The starting propylene polymer can be characterized in terms of a melt flow rate (MFR), measured at 230xc2x0 C. in accordance with ASTM D1238(1), and reported in grams per 10 minutes. The starting propylene polymer should have a MFR of about 3 to about 250, preferably about 10 to about 150, more preferably about 20 to about 100.
The starting propylene polymer is subjected to a visbreaking process which reduces its average molecular weight, resulting in a visbroken propylene polymer. The visbreaking may be accomplished using conventional techniques familiar to persons skilled in the art. For instance, the visbreaking may be accomplished using a peroxide to facilitate molecular scission of the propylene molecules. The visbreaking may also be accomplished using heat (often 300-400xc2x0 C.), radiation, shear (e.g., using an extruder), combinations of the foregoing techniques, or any other technique which accomplishes the desired level of molecular scission.
Preferably, the visbreaking is accomplished with the aid of a peroxide catalyst. Suitable catalysts include, for instance, alkyl hydroperoxides and dialkyl peroxides, as disclosed in U.S. Pat. No. 4,282,076, issued to Boynton. One suitable peroxide is 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane. Another suitable peroxide is 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane-3. These peroxides are available under the trade name LUPERSOL(copyright) from Pennwalt Corporation.
The peroxide may be added to the propylene polymer in a molten state at about 180-300xc2x0 C in an extruder, for instance. The amount of heat will affect the rate and extent of the visbreaking. The peroxide may be added at about 0.001-2.0% by weight of the propylene polymer, preferably about 0.1-1.0% by weight of the polymer, more preferably about 0.2-0.7% by weight of the propylene polymer.
The visbreaking conditions should be selected and controlled so that the visbroken propylene polymer exhibits only a relatively minor amount of degradation, in comparison to the starting propylene polymer. The visbroken propylene polymer should have an MFR that is about 1.0-3.0 times the MFR of the starting propylene polymer. The visbroken propylene polymer preferably has an MFR that is about 1.3-2.7 times the MFR of the starting propylene polymer, more preferably about 1.5-2.5 times the MFR of the starting propylene polymer. Also, the visbroken propylene polymer should have an MFR of at least about 10, preferably about 20-150, more preferably about 30-100, to render it particularly useful for melt spinning applications.
The visbroken propylene polymer may be used alone in a melt spinning process, or may be combined with one or more other polymers. For instance, the visbroken propylene polymer may be combined with one or more polymers selected from polyamides, polyesters, polyolefins, copolymers of ethylene and propylene, copolymers of ethylene or propylene with a C4-C20 alpha-olefin, terpolymers of ethylene with propylene and a C4-C20 alpha-olefin, ethylene vinyl acetate copolymers, propylene vinyl acetate copolymers, styrene-poly(ethylene-alpha-olefin) elastomers, polyurethanes, A-B block copolymers where A is formed of poly(vinyl arene) moieties such as polystyrene and B is an elastomeric midblock such as a conjugated diene or lower alkene, polyethers, polyether esters, polyacrylates, ethylene alkyl acrylates, polyisobutylene, poly-1-butene, copolymers of poly-1-butene including ethylene-1-butene copolymers, polybutadiene, isobutylene-isoprene copolymers, and combinations of any of the foregoing. Polyolefin homopolymers and copolymers are preferred as additional polymers. Polyethylene and polypropylene homopolymers and copolymers are most preferred.
If the visbroken propylene polymer is blended or alloyed with an additional polymer, it is generally preferred that the blending or alloying take place after the visbreaking of the single-site catalyzed propylene polymer. This way, the visbreaking process will not influence the properties of the additional polymer. When making blended or biconstituent filaments or fibers, the amount of visbroken propylene polymer relative to the additional polymer may vary considerably depending on the application. The polymer blend should include at least 10% by weight of the visbroken single-site catalyzed propylene polymer, preferably at least 25% by weight, more preferably at least 50% by weight.
The visbroken propylene polymer and one or more additional polymers may also be extruded adjacent each other in the form of bicomponent filaments or fibers. Again, the ratios of each polymer may vary considerably depending on the application. The bicomponent filaments should include at least 10% by weight of the visbroken single-site catalyzed propylene polymer, preferably at least 25% by weight, more preferably at least 50% by weight.
The nonwoven web produced by the melt spinning process may be a spunbond web, a meltblown web, a bonded carded web, an air laid web, or another type of nonwoven web, and may be present in a single layer or a multilayer composite including one or more nonwoven web layers. Whether the visbroken propylene polymer is used alone or in combination with another polymer, the primary functions of the visbroken polymer are to facilitate production of fine fibers (e.g. very fine fibers) having acceptable strength for various end use applications.
Nonwoven webs containing the visbroken single-site catalyzed propylene polymer can be manufactured using a wide variety of melt spinning processes, including conventional melt spinning processes. One suitable melt spinning process is described in U.S. Pat. No. 3,802,817, issued to Matsuki et al., which is incorporated herein by reference. That process may also be referred to as a partially oriented yarn (POY) fiber line. In that process, a curtain of melt spun filaments are extruded from a spinneret and drawn to a desired filament diameter with the aid of air jet streams applied on both sides of the curtain. The airjets are oriented such that they interact to create a suction force which draws the filaments following their extrusion. The average diameter of the manufactured filaments is influenced, to an extent, by the diameter of the spinneret openings as well as the tension force exhibited by the polymer material, which opposes the suction force exerted by the air streams.
In another type of POY fiber line, the filaments may be mechanically drawn using drawing rollers, for instance, instead of being air drawn. In each type of POY line, the filaments are drawn while in a molten or partially molten state, after being extruded from a spinneret.
Fibers containing the visbroken single-site catalyzed propylene polymer exhibit reduced tension at a given fiber drawing (e.g., mechanically driven rolls) speed. For instance, it has been discovered that fibers made entirely from a visbroken single-site catalyzed propylene polymer of a given MFR, exhibit less tension at a given fiber drawing speed than a similar reactor grade single-site catalyzed propylene polymer having the same MFR. Conversely, at a given tension, a higher fiber drawing speed is attained which results in fibers having smaller average diameters. The increase in attainable drawing speed also facilitates the manufacture of finer nonwoven fibers in other melt spinning processes, in which fiber diameter is controlled by suction air or different mechanisms. The improved ease of drawing, coupled with high fiber strength and integrity, also reduces the incidence of fiber breakage, damage, swelling, and other detrimental processing factors. Thus, higher production rates can be achieved without interference from these factors.
The nonwoven fibers produced can be in the form of substantially continuous filaments, or shorter (cut) staple fibers. A wide variety of nonwoven fiber diameters can be achieved depending on the melt spinning process employed, the process conditions, the specific characteristics of the visbroken single-site catalyzed propylene polymer, and whether the visbroken polymer is used alone or in combination with other polymers. While large diameter fibers can be produced, a key feature of the invention is the enablement of fine fiber production. The fibers produced using the visbroken single-site catalyzed propylene polymer may have diameters less than 1 micron to about 75 microns, preferably about 7 microns to about 30 microns, more preferably, about 15 microns to about 25 microns.
Nonwoven fabrics prepared according to the invention can be used in a wide variety of product applications including, in particular, personal care products. Personal care products include, without limitation, diapers, training pants, swim wear, absorbent underpants, baby wipes, adult incontinence products, feminine hygiene products, and the like. In absorbent products, the nonwoven fabric can be used as a cover sheet or containment matrix for an absorbent medium. The treated nonwoven fabric can also be used in medical products, including without limitation medical garments, underpads, absorbent drapes, bandages, and medical wipes.

Nonwoven fabrics prepared using visbroken single-site catalyzed polypropylene